A team of astronomers used a global network of telescopes to detect the lowest-mass dark object ever observed.
The discovery could guide future research into similar dark objects. Ultimately, these discoveries can help to rule out theories about the nature of dark matter, allowing scientists to understand the mysterious substance better.
The object emits no light, meaning the astronomers had to use a clever workaround to find it. Instead of directly detecting the object itself, they observed how its gravity distorts light passing nearby.
Searching for invisible objects
The team behind the discovery used a vast global network of telescopes to make their discovery.
These include the Green Bank Telescope (GBT) in West Virginia, the Very Long Baseline Array (VLBA) in Hawaiʻi, and the European Very Long Baseline Interferometric Network (EVN). According to a press statement, the EVN includes radio telescopes in Europe, Asia, South Africa, and Puerto Rico to create an “Earth-sized super telescope”.
They published their findings in two different papers in Nature Astronomy and Monthly Notices of the Royal Astronomical Society. They detail how the team discovered the object through gravitational lensing.
When the light of distant objects passes near another large cosmic object, it is curved and magnified. Astronomers often use this effect to peer further into the ancient universe than would otherwise be possible. In this case, the team used it to infer the existence of a dark object causing the effect.
Astronomers could infer the amount of matter in invisible objects based on the distortion.
“It’s an impressive achievement to detect such a low mass object at such a large distance from us,” Chris Fassnacht, co-author on the Nature Astronomy paper, from the University of California, Davis, explained in the press statement. “Finding low-mass objects such as this one is critical for learning about the nature of dark matter.”
Uncovering the mystery of dark matter
Through their observations, the team of astronomers determined that the dark object has a mass roughly a million times larger than our sun. Still, they don’t know exactly what it is. It could be an inactive dwarf galaxy, or a clump of dark matter 100 times smaller than any observed.
The discovery could shed new light on the nature of dark matter, the invisible substance that makes up roughly a quarter of the universe. Scientists, for example, have long wondered whether dark matter can exist in small clumps without a nearby star.
The mysterious cosmic object has the lowest mass of any dark object discovered via gravitational lensing with a global telescope network. Moving forward, the team believes their methods could help find similar objects.
“Given the sensitivity of our data, we were expecting to find at least one dark object, so our discovery is consistent with the so-called ‘cold dark matter theory’ on which much of our understanding of how galaxies form is based,” lead author Devon Powell, from the Max Planck Institute for Astrophysics (MPA), Germany, explained. “Having found one, the question is whether we can find more and whether the numbers will still agree with the models.”